(1) Field of the Invention
This invention relates to a surface modifier for a powdery or granular substance having a hydrophilic surface, such as a filler or pigment for polymeric compound. More particularly, it relates to a surface modifier for treating a powdery or granular substance having a hydrophilic surface with an aluminum chelate compound to modify this hydrophilic surface and improve the dispersibility of the powdery or granular substance in an organic medium.
(2) Description of the Prior Art
Ordinarily, a filler or pigment for a polymeric compound (hereinafter referred to as "filler or the like" for brevity) has hydrophilic functional groups and adsorbed water on the surface thereof whereby the surface of the filler or the like is kept hydrophilic. Accordingly, the filler or the like is poor in the oleophilic characteristic and it does not show good dispersibility or miscibility to organic media such as paint vehicles, printing ink vehicles and polymeric compounds. Therefore, if the filler or the like is used as it is, the gloss or opacitying power of a paint or printing ink is degraded or the strength of a composite plastic material is reduced. As means for eliminating this defect, many proposals have been made which include, for example, a method in which a surface active agent or metal soap is added together with the filler or the like and a method in which the filler or the like is treated with an organic silane type coupling agent. Furthermore, they include a method in which aluminum triacylate or its derivatives are incorporated in an organic medium to improve the dispersibility of the filler or the like in said organic medium (see U.S. Pat. No. 3,294,686), a method in which the filler or the like is treated with a titanium compound containing a partially hydrolyzed group and a method in which the filler or the like is treated with an aluminum alcoholate of a lower or higher alcohol or a partially acylated product thereof (see U.S. Pat. No. 3,905,936). These known methods are effective for improving the dispersibility of the filler or the like to some extent, but their modifying effect is not satisfactory, the production of the modifiers is not easy, they readily solidify or a large amount of a solvent is necessary because the solubility is poor.